Reclosable packages are widely used in the packaging of a variety of products, especially food. Reclosable packages are convenient in that after the initial opening, consumers can close and reseal the package to better preserve the enclosed contents. A critical factor in preserving the contents of any package is the integrity of the seals. Air and water tend to migrate more readily in packages having non-permanent seals. Thus, it is most desirable to use permanent seals wherever a seal is needed and a limited number of non-permanent seals.
Rigid packages are often utilized when the contents could be easily crushed or broken. Rigid packages provide structural support to protect the contents of the package such that the contents remain intact during transportation, storage, and handling. However, unlike a flexible package, the opening of a rigid package cannot be expanded by distorting the package due to the rigidness of the package. Thus, rigid reclosable packages generally have used a lid or cover which is removed when accessing the contents. But since these lids or covers employ non-permanent seals, the rigid package is more susceptible to the permeation of air and moisture after being reclosed.
Many packages use non-permanent, reclosable seals at the opening of the package. In one technique, the reclosable seal includes male and female closure profiles disposed on opposing surfaces of the package and configured to releasably interlock with each other. The male and female portions can be integral with the opposing surfaces, or nonintegral with the opposing surfaces but adhering thereto. The adherence of the male and female profiles is typically achieved by means of heat fusion. In another technique, the reclosable seal is a pressure-sensitive adhesive at opposing surfaces of the package adjacent the entrance.
U.S. Pat. No. 5,358,334 to Simonsen discloses a reclosable profile strip for packages which eliminates slippage between the two web portions of the profile strip. The reclosable profile strips are designed primarily for flexible packages.
U.S. Pat. Nos. 4,896,775 and 4,949,527 to Boeckman et al. disclose a reclosable tray for foodstuffs which encases its contents with a cover sealed to a rim of the tray through heat sealing or adhesives. Both the cover and the tray are flexible. A male and female interlocking connection lies between the cover and rim on one side of the tray. The cover can be pulled back such that the seal on the rim of the two sides adjacent the side having the male and female interlocking connection is detached and the contents of the package are revealed. The problem with this arrangement is that the two sides with the detached seal allow for the access of air and water when the package is closed after the initial opening.
A similar package is disclosed in U.S. Pat. Nos. 5,188,461 and 4,925,318 to Sorenson. In these patents, at least one side of a cover sheet has a peel seal weld attaching the cover sheet to a flange of a cup. Thus, this cover sheet can be pealed away to access the contents of the cup. Additionally, male and female reclosable interlocking portions exist on one side of the flange of the cup. Again, if the cover is pealed back slightly and resealed with the interlocking portion, air and water still may access the contents of the cup on those sides which are peeled back and have no reclosable interlocking portions.
A need therefore exists for a rigid reclosable package arrangement which overcomes the aforementioned shortcomings associated with the migration of air and water into the rigid package while still allowing access to the contents of the package.